Although Python makes sending e-mails relatively easy via the smtplib
library, Scrapy provides its own facility for sending e-mails which is very
easy to use and it’s implemented using Twisted non-blocking IO, to avoid
interfering with the non-blocking IO of the crawler. It also provides a
simple API for sending attachments and it’s very easy to configure, with a few
settings.

attachs (iterable) – an iterable of tuples (attach_name,mimetype,file_object) where attach_name is a string with the name that will
appear on the e-mail’s attachment, mimetype is the mimetype of the
attachment and file_object is a readable file object with the
contents of the attachment

These settings define the default constructor values of the MailSender
class, and can be used to configure e-mail notifications in your project without
writing any code (for those extensions and code that uses MailSender).